The present invention relates to bearings, and in particular to an abrasion resistant bearing for use in mixing machines for abrasive minerals.
In agriculture, it is desirable to enhance soils with certain minerals and nutrients such as gypsum, sulphur, potassium and nitrogen. Many growers have installed drip or sprinkler irrigation systems for their crops. These irrigation systems provide an efficient method for applying such minerals and nutrients to the soil. There are a number of well known mixing machines in use which provide different ways of mixing these minerals and nutrients with water for injection into irrigation systems. Among these are U.S. Pat. Nos. 4,812,045; 4,820,053; and 5,417,491. The dissolution machines described in these patents include a large mixing tank with an agitation apparatus inside where the mineral or nutrient is mixed with water. Large amounts of these materials are mixed with water in order to keep the material in suspension.
Unfortunately, these materials are very abrasive. Moreover, minerals such as gypsum will settle out very rapidly when agitation is stopped making it very difficult to then bring them back into suspension. As a result, it is often necessary to keep such materials actively agitated for long periods of time. The abrasive quality of these materials causes much wear on the bearings of the agitation assembly.
Existing agitation systems have been constructed using parts made out of cast iron and brass. The abrasive quality of materials such as gypsum causes significant wear on parts made of these materials resulting in continuous maintenance in the form of repair and replacement.
In 1982, Spraying Devices, Inc. of Visalia, Calif. developed a material made of glass filled nylon for use in the bearings of agitation systems. While this proved a great improvement over the cast iron and brass, the glass filled nylon still wore out too quickly.